Long-term follow-up of patients discontinuing bulevirtide treatment upon long-term HDV-RNA suppression

Antiviral therapy for chronic hepatitis delta: new insights from clinical trials and real-life studies

Chronic hepatitis D (CHD) is the most severe form of viral hepatitis, carrying a greater risk of developing cirrhosis and its complications. For decades, pegylated interferon alpha (PegIFN-α) has represented the only therapeutic option, with limited virological response rates and poor tolerability. In 2020, the European Medicines Agency approved bulevirtide (BLV) at 2 mg/day, an entry inhibitor of hepatitis B virus (HBV)/hepatitis delta virus (HDV), which proved to be safe and effective as a monotherapy for up to 144 weeks in clinical trials and real-life studies, including patients with cirrhosis. Long-term BLV monotherapy may reduce decompensating events in patients with cirrhosis. The combination of BLV 2 mg with PegIFN-α increased the HDV RNA undetectability rates on-therapy but not off-therapy, compared with PegIFN monotherapy. However, combination therapy, but not BLV monotherapy, may induce hepatitis B surface antigen (HBsAg) loss in some patients. The PegIFN lambda study has been discontinued due to liver toxicity issues, while lonafarnib boosted with ritonavir showed limited off-therapy efficacy in a phase 3 study. Nucleic acid polymer-based therapy is promising but large studies are still lacking. New controlled trial data come from molecules, such as monoclonal antibodies and/or small interfering RNA, that target HBsAg or HBV RNAs, which demonstrated not only profound HDV suppression, but also HBsAg decline.While waiting for new compounds to be approved as monotherapy or in combination, BLV monotherapy 2 mg/day remains the only approved therapy for CHD, at least in the European Union region.

Comparing methods for plasma HDV RNA quantification in bulevirtide-treated and untreated patients with HDV

Background & Aims

Accurate HDV RNA quantification is crucial for diagnosis and management of chronic hepatitis delta (CHD), yet a significant variability between assays exists. We compared three methods to quantify HDV RNA levels in untreated and bulevirtide (BLV)-treated patients with CHD.

Methods

Frozen plasma from untreated and BLV-treated patients with CHD were tested in a single-center retrospective study using three different assays: Robogene 2.0 HDV RNA Quantification Kit 2.0 (Roboscreen GmbH; limit of detection [LOD] 6 IU/ml on 7500 Fast Real-Time PCR System [Applied Biosystem]), EurobioPlex HDV PCR quantitative kit (Eurobio Scientific; LOD 100 IU/m) on CFX96™ real-time PCR detection system [Bio-Rad]), and AltoStar HDV RT-PCR RUO Kit 1.5 (Altona Diagnostics; estimated LOD <10 IU/ml) on the AltoStar®AM16.

Results

Overall, 431 plasma samples from 130 patients with CHD (69 untreated and 61 BLV-treated) were studied. Compared with Robogene 2.0, EurobioPlex reported higher HDV RNA levels (3.78 [0.70-7.99] vs. 4.69 [2.00-8.19] log IU/ml, p <0.0001), with viremia higher than >0.5 log in 160 (69%). Likewise, HDV RNA levels were higher with AltoStar than with Robogene 2.0 (3.32 [0.70-7.37] vs. 3.91 [0.19-7.54] log IU/ml, p <0.0001), with AltoStar reporting HDV RNA levels >0.5 log in 127 (52%). Although virological response rates (≥2 log decline vs. baseline) at Weeks 24 (Robogene 2.0 vs. EurobioPlex and AltoStar) and 48 (Robogene 2.0 vs. AltoStar) were similar across assays, rates of HDV RNA undetectability significantly differed between the three assays at Weeks 24 and 72 (p = 0.003 and p = 0.02, respectively).

Conclusions

HDV RNA levels quantified by EurobioPlex and AltoStar were 1 and 0.5 logs higher than those quantified by Robogene 2.0, respectively. HDV RNA undetectability rates during BLV treatment were assay-dependent.

Impact and implications

Management and diagnosis of chronic hepatitis delta (CHD) require standardized tests for HDV RNA quantification. Quantification of HDV RNA is significantly influenced by the quantification method, with EurobioPlex detecting approximatively 1 log and AltoStar 0.5 log IU/ml more than Robogene 2.0, respectively. The HDV RNA undetectability rates during BLV monotherapy significantly differed among assays. These findings are of clinical relevance as patients who achieve negative viremia during BLV monotherapy might be entitled to stop therapy successfully.

Clinical Pharmacology of Bulevirtide: Focus on Known and Potential Drug-Drug Interactions

Background: Hepatitis D virus (HDV) is a defective virus requiring co-infection with hepatitis B virus (HBV) to replicate, occurring in 5% of HBV+ patients. Bulevirtide (BLV) is now the first-in-class specific anti-HDV agent, inhibiting HDV binding to NTCP, with good tolerability and good virological and biochemical response rates. Currently, little is known about its pharmacokinetic/pharmacodynamic (PK/PD), as well as potential drug-drug interaction (DDI) profile. In this work we provide a systematic review of the current knowledge on these aspects. Methods: A literature review of PK, PD and DDI profiles of BLV was conducted from Pubmed and EMA websites. Experimentally tested interactions and hypothetical mechanisms of interaction were evaluated, mostly focusing on usually co-administered anti-infective agents and other drugs interacting on NTCP. Results: BLV shows non-linear PK, due to target-mediated drug disposition, so its PK as well as PD is expected to be influenced by interactions of other drugs with NTCP, while it is not substrate of CYPs and ABC transporters. In-vivo investigated DDIs showed no clinically relevant interactions, but a weak inhibitory effect was suggested on CYP3A4 in a work when used at high doses (10 mg instead of 2 mg). In vitro, a weak inhibitory effect on OATP transporters was observed, but at much higher concentrations than the ones expected in vivo. Conclusions: The drug-drug interaction potential of BLV can be considered generally very low, particularly at the currently approved dose of 2 mg/day. Some attention should be paid to the coadministration of drugs with known binding and/or inhibition of NTCP.

Current and future therapeutic options for chronic hepatitis D virus infection

In the last few years there have been innovations in HDV therapy which have brought new excitement in the scientific community also considering the few therapeutic opportunities. Recently, new molecular targets have been identified, both in monotherapy and in combination with peginterferon alpha (PegIFNα). Evaluating this review of the literature of the last ten years, HDV-related chronic hepatitis seems to have become a potentially curable disease, a statement that was unthinkable a few years ago. There are old and new weapons at our disposal. The old weapons are PegIFNα and recently PegIFN-lambda (PegIFNλ). PegIFNα, for which there are more data, appears to be an excellent combination regimen, if not contraindicated, both for Bulevirtide (BLV), data supported by important clinical trials and real-world studies, and probably for lonarfanib, although in the latter case the results are not yet definitive as the studies are fewer. However, data on long-term follow-up are needed.

Safety and efficacy of off-label bulevirtide monotherapy in patients with HDV with decompensated Child-B cirrhosis-A real-world case series

BACKGROUND AND AIMS

Chronic hepatitis D is the most debilitating form of viral hepatitis frequently progressing to cirrhosis and subsequent decompensation. However, the HDV entry inhibitor bulevirtide is only approved for antiviral treatment of patients with compensated disease. We aimed for the analysis of real-world data on the off-label use of bulevirtide in the setting of decompensated liver cirrhosis.

APPROACH AND RESULTS

We conducted a retrospective study in patients with HDV with decompensated liver disease at German, Austrian, and Italian centers. We included 19 patients (47% male, mean age: 51 years) with liver cirrhosis Child-Pugh B. The median MELD score was 12 (range 9-17) at treatment initiation. The median observation period was 41 weeks. Virologic response was achieved in 74% and normal alanine aminotransferase was observed in 74%. The combined response was achieved by 42%. The most relevant adverse events included self-limited alanine aminotransferase flares, an asymptomatic increase in bile acids, and the need for liver transplantation. Despite bile acid increases, adverse events were considered unrelated. Clinical and laboratory improvement from Child-Pugh B to A occurred in 47% (n = 9/19). Improvements in the amount of ascites were observed in 58% of the patients initially presenting with ascites (n = 7/12).

CONCLUSIONS

This report on off-label bulevirtide treatment in patients with decompensated HDV cirrhosis shows similar virologic and biochemical response rates as observed in compensated liver disease. Significant improvements were observed in surrogates of hepatic function and portal hypertension. However, this improvement was not seen in all patients. Controlled trials are needed to confirm the safety and efficacy of bulevirtide in decompensated HDV cirrhosis.

Advances in hepatitis delta research: emerging insights and future directions

OBJECTIVES

Hepatitis delta virus (HDV) is a defective virus needing the envelope provided by hepatitis B virus (HBV) in order to enter liver cells and propagate. Chronic HDV infection is considered the most severe viral hepatitis, resulting in accelerated fibrosis progression until cirrhosis and its complications (hepatocellular carcinoma, liver decompensation) compared with HBV mono-infected patients. Off-label treatment with interferon has represented the only treatment option in the last 40 years, resulting in suboptimal virological response rates and being limited by safety issues especially in patients with advanced cirrhosis. Recently, the first HBV-HDV entry inhibitor Bulevirtide (BLV) has been approved by the European Medicines Agency (EMA) for treatment of chronic compensated HDV.

METHODS

This review summarises most recent updates on HDV epidemiology, diagnosis and treatment, with a special focus both on clinical trials and real-life studies about BLV. An overview on new HDV compounds under development is also provided.

RESULTS

BLV, the HBV-HDV entry inhibitor, has shown promising safety and efficacy data in clinical trials and in real-life studies, also in patients with advanced cirrhosis and portal hypertension. However, according to EMA label treatment is currently intended long-term until clinical benefit and predictors of responses are still undefined. The potential combination with PegIFNα seems to increase virological and clinical responses. New compounds are under development or in pipeline for treatment of HDV.

CONCLUSION

After more than 40 years since HDV discovery, new treatment options are currently available to provide efficient strategies for chronic hepatitis Delta.

Management of chronic HBV-HDV patients chronic HBV-HDV infection: A review on new management options

Hepatitis D virus was first described by Mario Rizzeto in 1977, and it is considered chronic viral hepatitis with the poorest prognosis. Despite its discovery almost 50 years ago, progress in its diagnosis and treatment has been scarce until recent years. The approval of bulevirtide has shed some light for patients with Chronic Hepatitis D, although important gaps regarding its use in therapy as well as about the epidemiology and diagnosis of the disease need to be addressed.

Hepatitis D Virus and HBsAg Dynamics in the era of new Antiviral Treatments

PURPOSE OF REVIEW

Hepatitis D virus (HDV) infection is the most severe form of chronic viral hepatitis, with no FDA-approved therapy. Progress in the development of effective HDV treatments is accelerating. This review highlights how mathematical modeling is improving understanding of HDV-HBsAg-host dynamics during antiviral therapy and generating insights into the efficacy and modes of action (MOA) of new antiviral agents.

RECENT FINDINGS

Clinical trials with pegylated-interferon-λ, bulevertide, nucleic acid polymers, and/or lonafarnib against various steps of the HDV-life cycle have revealed new viral-kinetic patterns that were not observed under standard treatment with pegylated-interferon-α. Modeling indicated that the half-lives of circulating HDV and HBsAg are ~ 1.7 d and ~ 1.3 d, respectively, estimated the relative response of HDV and HBsAg during different antiviral therapies, and provided insights into the efficacy and MOA of drugs in development for treating HDV, which can inform response-guided therapy to individualize treatment duration. Mathematical modeling of HDV and HBsAg kinetics provides a window into the HDV virus lifecycle, HDV-HBsAg-host dynamics during antiviral therapy, and the MOA of new drugs for HDV.